1. Field
The following description relates to a fixing device and an image forming apparatus including the same.
2. Description of the Related Art
Conventional fixing devices, for example, a fixing device disclosed in Japanese Patent Publication Gazette No. 2010-66583, includes a fixing belt having a halogen lamp therein and a pressing roller arranged in pressure-contact to the fixing belt to form a nip portion between the pressing roller and the fixing belt. A non-fixed image may be formed on a recording medium such as paper passing through the nip portion, and the fixing device heats and presses the non-fixed image to fix the non-fixed image onto the recording medium.
Recently, there has been a demand for high productivity and high energy efficiency with respect to an image forming apparatus adopting a laser scheme. To improve productivity and energy efficiency, a low-heat-capacity fixing belt for improving heat efficiency may be arranged on a fixing device mounted on an image forming apparatus. For example, in the low-heat-capacity fixing belt, a halogen lamp for applying a certain amount of heat to the fixing belt may be arranged, and in this case, heat generated by light of the halogen lamp may be instantly transferred in a thickwise direction of the fixing belt, but may not be delivered in a widthwise direction of the recording medium, making it difficult to maintain a temperature in the widthwise direction of the recording medium constant. Thus, to adapt the halogen lamp to a different-width recording medium, a long halogen lamp corresponding to a wide-width recording medium may be used, and in this case, if a narrow-width recording medium is used, an unnecessary heating area may be generated in the fixing belt. That is, a problem may occur in efficiently heating the fixing belt to correspond to a different-width recording medium.
To solve these problems, the fixing device disclosed in Japanese Patent Publication Gazette No. 2010-66583 includes a shielding plate arranged between the halogen lamp and the fixing belt and an opening portion corresponding to the heated region of the fixing belt. In the fixing device disclosed in Japanese Patent Publication Gazette No. 2010-66583, the shielding plate moves along the widthwise direction of the recording medium and the size of the opening portion is adjusted, such that the width of the heated region included in the fixing belt may correspond to the different-width recording medium.
However, in the fixing device disclosed in Japanese Patent Publication Gazette No. 2010-66583, some of the heat generated by the light of the halogen lamp, i.e., heat applied to a portion blocked by the shielding plate, is not actually used, and thus, the fixing device may not be favorable in terms of heat efficiency.